1. Field of the Invention
The invention concerns a lighting arrangement for a room or space which can be closed off, having a fire-proofing ceiling, in particular for a freight compartment of passenger aircraft, and which provides for lighting units arranged in fire-proofing ceiling.
In passenger aircraft the freight compartment or compartments is or are generally disposed beneath the passenger compartment, in which case the floor surface of the passenger compartment substantially simultaneously represents the ceiling of the freight compartment. Reference is made to FIGS. 3 and 4 showing by way of example the principle of a conventional lighting system for such freight compartments.
2. Discussion of the Prior Art
The freight compartment 2 of the passenger aircraft, which is arranged beneath the passenger compartment 1, is defined by the ceiling 3, the floor 4 and the side walls 5. Provided in the ceiling 3 of the freight compartment 2 are one or more lighting units 6 which only partially illuminate the freight compartment 2 in the manner indicated by the light cone 9. As can be seen from the portion of the arrangement shown on an enlarged scale in FIG. 4, the lighting unit 6 has in general one or two fluorescent lamps 7 with corresponding electronics 8. The fluorescent lamps 7 are disposed in a fire-resistant housing, for example a high-quality steel light housing 10 which has a plug housing 11 for the electrical connections of the light electronics 8. The high-quality steel housing 10 is closed at its side that faces towards the floor 2 by a translucent cover 12. The cover is generally arranged in the plane of the freight compartment ceiling 3 so that the lighting unit 6 is disposed above the freight compartment 2 and extends into the passenger compartment 1. The lighting unit 6 is secured to the freight compartment ceiling 3 by suitable fixing devices 13.
An essential component in that structure which is shown in FIGS. 3 and 4 is the freight compartment ceiling 3 which is necessarily in the form of a fire-proofing wall between the freight compartment 2 and the passenger compartment 1. That fire-proofing wall may also not be interrupted by the lighting units 6, for safety reasons. Therefore, with those conventional lighting systems, it is necessary for the lighting unit itself, that is to say in particular the housing 10, the cover 12 and the fixing devices 13, also to be in the form of a fire wall structure. Added to that is the fact that, with these relatively large lighting units 6 which generally involve a dimension between the fixing devices 13 at both sides of the lighting unit 6 of about 20 cm, a relatively large passage opening 19 has to be provided in the freight compartment ceiling 3 to fit the unit therethrough, whereby the floor load-carrying capability of the passenger compartment 1 is noticeably restricted.
In addition for example EP-A2-0 795 468 discloses a lighting system for passenger cabins of passenger aircraft. The lighting arrangement disclosed in that publication affords a unitary system which ensures minimum weight and a high level of reliability by virtue of the arrangement in the passenger cabin of optical waveguides which start from at least one central light source and which are connected to the most widely varying lighting units in the passenger cabin. In contrast to the above-discussed situation of lighting the freight compartment however, illumination of the passenger cabin does not involve the problems of limited floor load-bearing capability and designing the lighting units in the form of fire-proofing elements.